Inclusive cross section and double helicity asymmetry for rho(0) production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton. (Article No 051106)
2007
Abstract
The PHENIX experiment presents results from the Relativistic Heavy Ion Collider 2005 run with polarized proton collisions at root s=200 GeV, for inclusive pi(0) production at midrapidity. Unpolarized cross section results are given and described well for p(T) 2 GeV/c, by perturbative QCD.
Double helicity asymmetries A(LL) are presented based on a factor of 5 improvement in uncertainties. These measurements are sensitive to the gluon polarization in the proton.
Using one representative model of gluon polarization it is demonstrated that the gluon spin contribution to the proton spin is significantly constrained.